The present invention relates to a data bus, preferably for an aircraft. In particular, the present invention relates to a data bus system having a data bus terminal, a terminal for connection and operation using a data bus, and a data transmission method to transmit data between a data bus and a terminal.
Currently, in transformationally coupled linear data bus systems in aviation having separate transmitting and receiving lines, two transformers are used in order to couple the data bus to the terminal and vice versa. Terminals may be aircraft systems, devices, or sensors, for example. The transformational coupling is necessary in safety-critical systems in order to achieve the required operational reliability. The known buzzword in this regard is electrical isolation of data bus and terminal. Such data bus systems are described, for example, in the ARINC 629 Specification MIL STD 1553 Specification.
However, the signal level on the data bus is disadvantageously damped by each and/or each further transformer, since each individual transformer generates reflections which deform the useful signal. Furthermore, the use of transformers is expensive. In addition, if there is a large number of terminals, the transformers represent a relatively large weight.
Direct usage of a transformer for transmission and reception channels through parallel connection of the two spur lines which connect the bus lines to the terminal is not recommended, since the sensitive input circuit of the receiver in the terminal may be overloaded by the high output of the transmitter and, in addition, a possible short-circuit in the receiver of the terminal blocks the transmitter of this terminal.